The invention relates to a chain elevator which comprises an elevating chain made up of links attached to each other, whereby the planes formed by adjacent links are primarily at a 90.degree. angle in relation to each other and which chain has a fixed end; an elevating element having a driven chain gear arranged to it, the elevating chain being led to couple with the driven chain gear from the fixing point of the fixed end of the elevating chain located above the driven chain gear in such a manner that the elevating element hangs on the elevating chain; and a driving chain gear located above the driven chain gear, the elevating chain being led to couple with the driving chain gear from the driven chain gear, whereby the plane formed by each elevating chain link in said coupling is substantially at a 45.degree. angle in relation to the shaft of the driving chain gear.
The invention also relates to a chain elevator which comprises an elevating chain made up of links attached to each other, whereby the planes formed by adjacent links are primarily at a 90.degree. angle in relation to each other and which chain has a fixed end; an elevating element having a driven chain gear arranged to it, the elevating chain being led to couple with the driven chain gear from the fixing point of the fixed end of the elevating chain located above the driven chain gear in such a manner that the elevating element hangs on the elevating chain, whereby the plane formed by every second link of the elevating chain in said coupling is substantially parallel with the shaft of the driven chain gear and the plane formed by every other link is substantially perpendicular with said shaft; and a driving chain gear located above the driven chain gear, the elevating chain being led to couple with the driving chain gear from the driven chain gear.
A conventional chain elevator, i.e. the one described last in the above, is one in which every second chain link plane is, when coupled with both the (freely rotating) driven chain gear and the driving chain gear (drive gear), parallel with the shaft of the chain gear and every other chain link perpendicular with it. In this solution, only every second link is capable of transmitting the power of the driving chain gear to the elevating chain.
A more advanced solution, i.e. the one described first in the above, is a 45.degree. chain drive in which the elevating chain runs through the chain gears so that the plane of each link is always at an approximately 45.degree. angle in relation to the chain gear shafts. As compared with the conventional chain drive, the 45.degree. chain drive provides, for instance, the following advantages: all links in the elevating chain participate in power transmission when coupled with the driving chain gear and the polygon effect (i.e. the variation in elevating speed and force caused by the polygon-form of the chain gear) lessens. Thus, a 4-pocket chain gear in a 45.degree. chain drive, for instance, achieves the same properties as an 8-pocket chain gear in a conventional chain drive. Owing to this, it is possible to use smaller chain gears with certain specifications (minimum number of load-bearing pockets and the amount of the polygon effect). Then the load-bearing torque of the driving chain gear, which at the same time is the torque related to this chain gear, becomes smaller. The required transmission ratio of the gear is also smaller.
However, the 45.degree. chain drive also has significant drawbacks, because the forces between the elevating chain and the driven chain gear are extremely disadvantageous for both the chain and the chain gear. Therefore, both wear quickly and in particular when used in a drive which has the same chain length all the time and consequently the same location in the chain runs repeatedly through the driven chain gear. In such a case, there is an actual danger of a chain break.